Hydrodymanic torque converters

ABSTRACT

A hydrodymanic torque converter comprising a toroidal working chamber having a fluid outflow region, a fluid inflow region, and inner and outer transition regions. A ring of pump blades are located essentially in the outflow region, and a ring of guide blades and rings of turbine blades are located generally in the inflow region. At least a portion of one of the blade rings is positioned in one of the transition regions and includes blades which are twisted three-dimensionally by differing amounts along their lengths while the blades of the remaining rings are essentially two-dimensional in that they are of the same twist angle along their lengths.

United States Patent 1 Ahlen ]March 20, 1973 [s41 HY-DRODYMANIC TORQUE CONVERTERS t [75] Inventor: Karl Gustav Ahlen, Stockholm,

Sweden [73] Assignee: S.R.M. Hydiomekamik AB,

Stockholm-Vallingby, Sweden [22] Filed: Aug. 4, 1971 [21] App]. No.: 168,826

[30] Foreign Application Priority Data March 5, 197] Great Britain ..6l53/7l [52] US. Cl ..60/362 [51] Int. Cl. ..Fl6d 33/00, Fl6h 41/00 [58] Field of Search ..60/54 {56] References Cited UNITED STATES PATENTS 2,306,758 12/1942 Schneider et al ..60/54 2,377,825 6/1945 Teagno ..60/54 3,l99,377 8/1965 Knowles et a]. ..60/54 3,543,517 12/1 970 Ahlen ..60/54 Primary Examiner-Edgar W. Geoghegan Attorney-Larson, Taylor & Hinds [5 7 ABSTRACT A hydrodymanic torque converter comprising a toroidal working chamber having a fluid outflow region, a fluid inflow region, and inner and outer transition re gions. A ring of pump blades are located essentially in the outflow region, and a ring of guide blades and rings of turbine blades are located generally in the inflow region. At least a portion of one of the blade rings is positioned in one of the transition regions and includes blades which are twisted three-dimensionally by differing amounts along their lengths while the blades of the remaining rings are essentially twodimensional in that they are of the same twist angle along their lengths.

22 Claims, 26 Drawing Figures PATENTEDMARZOIHB v 3,721 090 SHEET 10F 8 PRIOR ART EDHARZO I975 PATENT SHEET 30F 8 PATENTEDMARZO 197s SHEET 0F 8 E525 ENQQNRRNNHEE H PATENTEDMARZOIEIB 3,721.090 SHEET GDP 8 LOSSES IN PERCENT OF THE TOTAL VELOCITY HEAD PATENTED MAR 2 0197s sum 8 UF 3 MYDRUDYMANIC TORQUE CONVERTERS This invention relates to hydrodynamic torque converters.

Hydrodynamic torque converters today are very highly developed machines when considered both from the point of view of the techniques employed in their manufacture and the techniques employed in order to obtain a satisfactory high performance for a particular field of application.

Due to the necessarily high capital investment in the tools employed in the manufacture of torque converters, it is a natural aim of manufacturers to reduce the manufacturing costs per converter and to be able to accurately reproduce the converters within acceptable manufacturing tolerances so that consistently high performance characteristics are obtained.

During the last 30 years many different types of torque converter blade systems have been developed and a number of these systems are currently in production. The fact that many types of blade systems are currently in production indicates, inter alia, that hitherto it has not been possible to produce a single blade system which will enable performance characteristics to be varied as required for different applications and simultaneously attain the high performance demanded by the different applications.

It is generally understood that such improvements as widening the Ms range, that is, the torque absorption range, or, obtaining a higher stall torque ratio, or, a higher utility ratio, or, a higher peak efficiency without reducing any of the other performance characteristics would naturally lead to a greater potential market for a blade system. An increased market would also be obtainable if the same blade system could be used for a greater range of torque and speed. To this end it is desirable to improve the strength of the blade system which is principally designed for manufacture by diecasting techniques (or casting techniques which do not use cores) without increasing manufacturing costs beyond that which is acceptable and offset by way of improved performance and versatility for the lowest power range.

According to one aspect of the present invention, there is provided a hydrodynamic torque converter including a toroidal working chamber comprising an inflow part, an outflow part and inner and outer transition regions connecting the inflow and outflow parts, and a ring of pump blades, a ring of turbine blades and a ring of guide blades in the working chamber, characterized in that at least a portion of one of the blade rings, i.e., either an integral port or a separate part of said blade ring, is positioned in a transition region between the inflow and outflow parts, in that the blades of the said portion of the blade ring have different outlet angles along the length of the profile and in that the blades of the remaining blade rings having substantially two-dimensional blades, as hereinafter defined.

Preferably, the blades of the said portion of the blade ring are three dimensional as hereinafter defined. Preferably, also, one of the three-dimensional blades does not overlap an adjacent three dimensional blade. The three-dimensional blades serve to adjust the flow of fluid within the working chamber and increase the overall efficiency of a torque converter in which the remaining blades are two-dimensional.

In a torque converter according to this invention, even the three-dimensional blades can be cast using a casting process which does not involve using cores. Thus, all the blades rings can be cast using die casting techniques.

The three-dimensional ring of blades is preferably a turbine ring disposed to direct and control fluid flow to the inlet of a ring of pump blades. The three-dimensional ring allows the stream or flow pattern of fluid in the working chamber to be corrected in such a way that conditions approaching more closely to ideal inlet conditions are obtained not only with respect to the pump inlet conditions but also with respect to the inlet conditions for all blade rings along substantially the whole length of the blades.

When the fluid stream enters the blade rows in the actual direction for which the blades are designed, the entrance losses are small. This is especially the case for the type of blades utilized in torque converters using the so-called and well known Lysholm blade profile. However, at extreme inlet conditions the entrance losses rise rapidly, and these losses restrict the quantity of fluid circulated which, in its turn, tends to give even more unfavorable inlet conditions in a kind of chain reaction. When a die-cast two dimensional blade system is used this, in itself, means a certain loss of performance, because the possibility to adjust the fluid stream over the total length of such blades does not exist. When, however, a blade system according to the in vention is used, this drawback is overcome and diecasting techniques can still be used for making the three-dimensional blade row, which is used for correct ing the fluid flow pattern in the working chamber. The effect obtained is an increased efficiency in the low and high speed ratio fields due to the fact that a reduction in loss at one blade entrance (in effect due to increased fluid circulation in itself) gives an increased efficiency at the entrance of the remaining blades. The blade system according to the invention gives at the same time high stall torque-ratio and high efficiency at speed ratios even above 1. When a second ring of turbine blades is parted according to the invention the utility range is increased by more than 15 percent.

According to a second aspect of this invention there is provided a hydrodynamic torque converter having a toroidal chamber for working fluid, the working chamber comprising an inflow part, an outflow part and inner and outer transition regions connecting the inflow and the outflow parts, a ring of pump blades in the outflow part, at least first and second rings of turbine blades and at least a ring of guide blades in the inflow part, characterized in that the second ring of turbine blades isdivided into first and second pai'ts, the blades of the first part being located principally in the inflow part of the working chamber, and the blades of the second part being located principally in the inner transition region and serving to control the flow condition of fluid at the inlets of at least the blades of the pump ring.

According to another aspect of this invention there is provided a hydrodynamic torque converter having a toroidal working chamber comprising an inflow part, and outflow part and inner and outer transition regions connecting the inflow and outflow parts, a ring of pump blades in the outflow part, and a first ring of turbine blades and a ring of guide blades in the inflow part; a second ring of turbine blades divided into at least first and second parts of blade rings, the said first part being located in at least the inflow part and having twodimensional blades (as herein defined) which extend principally radially of the inflow part, and the said second part having three-dimensional blades (as herein defined) which are located in at least the inner transition region of the working chamber for directing fluid in the working chamber to the ring of pump blades, the said first and second parts of the second turbine being rotationally fixed relatively to each other.

Conveniently, the first and second parts of the second turbine are carried on a turbine member which is adapted to be mounted on a turbine shaft by, for example, a spline connection. The blades of the first part of the second turbine serve to transmit or carry-over torque from the inner core of the torque converter and the turbine shaft and are, preferably, cast integrally with the turbine members.

In this specification, the term two-dimensional means that the blades are tapered only in one direction along their length and the cross-section of the blades taken in planes normal to the major axes of the blades are of normally the same basic form differing only in size as the blades taper. The two-dimensional blades are sometimes referred to as single-curvature blades.

In this specification also, the term three-dimensional" means that, in addition to the blades having similar or different cross-sections at different position along the length of the blades, elemental transverse sectional portions of the blades may be angularly displaced relative to the longitudinal axis (which may be curved or linear) of the blades so as to create a twisted appearance which may, in certain cases, by similar to that of an aircraft or ships propeller blade. The threedimensional blades are sometimes referred to as double-curvature" blades.

The two-dimensional blades of the first part of the second turbine ring are preferably manufactured using die-casting techniques and the amount of taper along the length of the blades may simply be the draw or draft" necessary for withdrawal of the blades from the moulds after casting. Preferably, the two-dimensional blades are cast integrally with an annular support having a shape which conforms to the shape of the appropriate part or parts of the toroidal working chamber in which the first part is disposed.

The three-dimensional blades of the second part of the second turbine ring may be manufactured by any known precision casting process such as lost-wax process. However, due to the fact that this blade ring has radial blades which do not overlap, it can be die cast on cast using any normal process without cores even through the blades are three-dimensional Thus, in effect, a three-dimensional second turbine is obtained without casting using cores or the ring being assembled from a number of individual components. Conveniently, the blades of the second part, which may be steel or an alloy steel, are cast integrally with at least one annular and, preferably, two annular blade supports thereby permitting one second part to be readily exchanged for another in accordance with the inlet conditions necessary for the other blade rings to achieve performance in a required torque absorption range. The annular blade supports for the three-dimensional blades of the second part are, conveniently, and in a similar way to the annular support for the blades of the first part, shaped to conform to the shape of the appropriate part or parts of the toroidal working chamber in which the second part is disposed.

It will, therefore, be appreciated that the first part of the second ring of turbine blades serves primarily to transmit torque whereas the second part thereof serves primarily to control the flow conditions of the fluid at the inlets to at least the blades of the pump ring and along substantially the whole length of the blades. In order to vary the inlet flow conditions, the threedimensional blades may be formed with trailing portions which are angularly disposed relative to the inlet portions measured in the direction of fluid flow in the working chamber. Variation of the outlet angles of the trailing portions of the three-dimensional blades assists in the balancing of those forces in the working fluid which tend to impart different speeds to the fluid at different regions along the length of the blades.

The outlet angles of the trailing portions of the threedimensional blades may be varied to adjust the direction of fluid flow along the length of the outlet portions of the pump blades. The second part of the second turbine ring is, conveniently, located between the inner core of the turbine hub and retained in such a rotational position relative to the first part of the second turbine that the inlet of the blades of the second part is in general alignment with the outlets of the blades of the first part. The blades of the second part of the second turbine are rotationally fixed relative to the inner core of the working chamber and the turbine hub or outer periphery of the working chamber. If desired, the blades of the second part of the second turbine may be mounted for angular displacement about their axes of symmetry in order to vary the angular position of the said blades relative to the blades of the first part of the second turbine.

The mechanism for angularly displacing the blades of the second part of the second turbine ring may be a servo motor located in the turbine hub cooperating with lever arms on the blades for setting the blades in any position between two extreme positions. The fluid pressure for the servo motor may be introduced through the turbine shaft and the pressure thereof modulated by a modulation valve.

The invention will now be described, by way of example, with reference to the accompanying drawings of which FIG. 1 is included for comparative purposes. In the drawings:

FIG. I shows, in longitudinal cross-section, a well known S.R.M. hydrodynamic torque converter manufactured by the present assignee;

FIG. 2 shows basically the same torque converter as FIG. I and modified in accordance with the present invention;

FIG. 3 is a part section through a first part of a second turbine blade ring;

FIG. 3A is a view of the first part of the second turbine blade ring taken in the direction of arrow 3A in FIG. 3;

FIG. 3B is an elevation of a blade of the first part of the second turbine ring and FIGS. 3C and 3D show various sections of the blade taken along similarly numbered section lines as FIG. 3B;

FIG. 4 shows the second part of the second turbine in end elevation looking from left to right in FIG. 2;

' FIG. 4A is a longitudinal section of the second part of the second turbine;

. FIGS. 48, 4C and 4D show sections of the blades of the second turbine part taken on sections B-B, C-C and D-D of FIG. 4;

FIGS. 5, 5A, 5B and 5C are sections taken along similarly numbered section lines as FIG. 1;

FIG. 5D is an enlargement of FIG. 5A;

FIGS. 6, 6A and 6B are blade sections taken along similarly numbered section lines as FIG. 2;

FIG. 6C is an enlarged view of FIG. 6A;

FIG. 7 is a graph showing the loss in velocity head of the blade system used in the torque converter of FIG. 2.

FIG. 8 is a cross-sectional view of a torque converter showing a means for turning the blades of the second part of the second turbine ring about their axes;

FIG. 9 is a sectional view taken along line 99 of FIG. 8;

FIGS. WA and 10B are sectional views taken along line 1l0-IIIt of FIG. 8 and showing the blades in the closed and open conditions, respectively.

FIG. I shows, in longitudinal cross-section, a well known form of hydrodynamic torque converter developed by the assignee of this application S.R.M. Hydromekanik AB of Stockholm, Sweden and commonly referred to as the S.R.M. torque converter. The

Y converter has a rotatable and split casing 1 containing a toroidal chamber 2 for a working fluid. The toroidal chamber consists of an outflow part, an outer transition region, an inflow part and an inner transition region represented by arrows 2A, 2B, 2C and 2D respectively. The direction of the arrows indicate the direction of fluid flow but do not, of themselves, indicate the precise extent of the corresponding parts and regions which fare naturally into one another. The casing is directly or indirectly connected to a prime mover via splines IA.

Within the toroidal chamber there is mounted a blade system consisting of a ring of pump blades P mounted in the outflow part 2A whereas first and second rings of turbine blades TI and T2 and a ring of guide blades G are mounted in the inflow part 1C. The pump blades P are cast integrally with part 11B of the rotatable casing 1A and secured by bolts 2E to part 3A of an inner core.

The first ring of turbine blades T1 are cast integrally with an annular member TIA and, in a similar manner, the guide blades G and the second ring of turbine blades T2 are cast integrally with annular members GA and TZA. The blades of the first turbine ring T1 are secured by bolts TllB to part 38 of the inner core whereas the blades of the second turbine are, in similar manner, bolted to part 3C of the inner core. The blades of the guide ring G are bolted to an annular disc 3D which constitutes a fourth part of the inner core.

The annular member TZA which carries the blades of the second ring of turbine blades is connected to output shaft 0 by a spline connection 4. The output shaft is supported on a roller bearing 5. Surrounding the output shaft O is a hollow shaft 6 which is connected to the annular guide member GA by a spline connection 6A. The hollow shaft 6 supports a roller bearing 7, the outer race of which supports part 1C of the split rotatable casing 10. Bolted to the part IC and sealingly cooperating with the hollow shaft 6, is an annular gear element 8 having gear teeth 8A.

FIG. 2 is generally similar to FIG. 1 and like parts bear the same reference numerals. The torque converter of FIG. 2 shows certain modifications in accordance with the present invention and, in particular, one way in which the second ring of turbine blades T2 is divided into first and second parts designated T2M and T2N respectively. From FIG. 2 it will'be seen that the blades T2M extend into the inflow section 2D and terminate at their outlet edges in a plane which is mutually perpendicular to the axis of rotation of the output shaft 0. The blades T2M are, as in the case of the blades T2, in the construction shown in FIG. 1, cast integrally with the annular turbine member T2A. The second part of the second ring of turbine blades T2N is cast integrally with an outer ring T20 and inner ring T2i. The internal surface of the outer ring T20 and the internal surface of the inner ring T2i are shaped to conform with the appropriate surfaces of the toroidal working chamber 2.

FIG. 2 also shows a blade ring P1 in the outer transitional region formed as an extension of the pump ring and having three-dimensional form. This ring can be used together with or instead of a three-dimensional blade ring in the inner transitional region.

The construction and formation of the first and second parts of the second ring of turbine blades are shown in greater detail in FIGS. 3, 3A, 3B, 3C and 3D and FIGS. 4, 4A, 4B, 4C and 4D.

FIG. 3 is a part-longitudinal section of the annular turbine member TZA showing one of the turbine blades constituting ring T2M. A spigot T2M' assists location of the said blade within a corresponding socket 3C formed in part 3C of the inner core. The annular turbine member T2A' has a recess T2R for receiving the second part of the turbine blade T2N. FIG. 3A is an end view of FIG. 3 taken in the direction of arrow 3A and showing the general two-dimensional form of the blades T2M. FIGS. 3C and 3D show the shape of the two-dimensional blades in greater detail and, for ease in understanding, the several sections are designated by the same Roman numerals as the corresponding section planes shown in FIG. 3B.

FIGS. 4 4D show the second part T2N of the second turbine and in greater detail. Different sections of the blade taken on lines B-B, C-C and D-D of FIG. 4 are shown in FIGS. 4B, 4C and 4D respectively. In FIGS. 4B, 4C and 4D, or designates the blade outlet and b is the minimum distance between adjacent blades of the ring or, in other words, the throat portion of the flow channel between adjacent blades. In FIGS. 48, 4C and 4D the angles dare 55 and respectively.

FIGS. 5, 5A and 5B show sections through the pump blades, first turbine blades and the guide blades of FIG. ll, respectively. In FIGS. 5A, 5B, 5C, the relative inlet angle of fluid entering the guide ring and the turbine ring at stall, that is, the pump turning at normal speed and the turbine stationary, is indicated at Ist. The arrow Ish indicates the direction of the relative inlet velocity at shaft point, that is, the point when the ratio vi /n and the efficiency of the torque converter are equal where n, is the speed of the pump and n is the speed of the turbine. The angle of divergence between Ist and Ish generally indicates the useful range of a torque converter and this is designated Additional sufflxes a, b and c to Ist, and Ish and 0: indicate values thereof at sections a-a, bb and cc of FIG. 1. Inlet at stall is indicated at Istb and I for an inlet direction at speed ratio 1.0 on section bb of FIG. 1.

In FIGS. A, 5B and 5C, 0. is the angle between the lines determinative of the outlet angle of a blade and the line I, representing the direction of optimum inlet flow to the blade. In other words :1) is the angle of deflection of the flow channels formed between adjacent blades.

FIG. 5D is an enlargement of the blades of the first turbine ring of FIG. 5A and shows also the field 'y between the inlet direction at stall and the inlet direction at speed ration 1.0 occurring on section b of FIG. 1 and for which the blade is designed. FIG. 5D also shows the inlet field for the sections a and c of FIG. 1 for the first turbine. The change in position of the fields influences the efficiency as the total spread of the inlet at stall to the total spread of the inlet at shift point, that is 7 total, is considerably larger than FIGS. 6, 6A and 6B show sections through the pump blades, the first turbine blades and the guide blades of FIG. 2, and inlet direction at stall and the inlet direction at speed ratio 1.0, which gives the inlet field are shown for blades of the first turbine ring.

FIG. 6C is an enlargement of the blades of the first turbine of FIG. 6A with the inlet field valid for the section b of the first turbine as also shown in FIG. 6 but, in addition, FIG. 6C shows the inlet field at sections a and c of FIG. 2 narrowed relative to the corresponding angles shown in FIG. 5D due to the twisting of the threedimensional blades in the region of the trailing or outlet edge of the second part of the second turbine ring TZN.

FIG. 7 shows a normal loss in velocity head ofa blade of the type used in the torque converter of the present invention and illustrates the importance of narrowing the width of the field since the losses increase rapidly at extreme inlet blade angle.

A test employing a blade system of the present invention showed a considerable improvement in efficiency obtained especially at high speeds and resulted in a 60 percent efficiency for a four blade ring converter system having a speed ratio n /nl as high as 1.1 and at the same time retaining a high stall torque ratio.

It is considered that one of the most reliable techniques for manufacturing components of a torque converter with a sufficiently high dimensional accuracy and at an acceptable cost level is die-casing or a similar method which does not involve the use of cores. Such methods also lend themselves to mass production. As soon as a casting method necessitating cores is used, dimensional accuracy is sacrificed, at least in so far as that necessary for high performance torque converters. Therefore, the value of a modified blade system having an attendant higher performance, is related in no small way to the manufacturing techniques employed. Unfortunately, a blade system with only two-dimensional blades is, in some respects, unable to guide the flow of the fluid in the working chamber in such a way that the best performance is obtained. In order to obtain good flow conditions it is necessary to take into account other factors, such as extending the pump into the outer transition region between the outflow and the inflow parts of the circuit to obtain high Ms values, which in itself tends to produce an unfavorable inlet condition to the first ring of the turbine blades. Further, with a two-dimensional blade system it is not possible to design a second turbine which gives good inlet conditions for different Ms ranges and this limits the possible Ms range obtainable using a two-dimensional blade system.

In a torque converter working chamber there are many factors which tend to twist the fluid stream or cause a non-streamline flow of the fluid. Some factors tend to accelerate the flow of the fluid in the region of the inner core and to slow down the flow of fluid along the outer periphery of the chamber. Also it will be noted that as the distance the fluid has to travel as it passes around the chamber is less in the region of the inner core than in the region of the outer periphery of the chamber. Obviously such factors lead to a spread of the extreme inlet conditions to the blades in the way shown in FIG. 5D, and this has a smaller effect the more the pump outlet extends into the transition region. At the same time, the fluid flow conditions thereby existing cause difficulties in relation to the pump entrance.

Our investigations show that when the inlet direction to a blade is extreme in any direction the losses increase rapidly which, to a certain degree balances the stream. We have, moreover, found that a more favorable overall balance is obtained if the total pressure head at different sections along the length of the blades can be balanced (even on a blade system with two-dimensional blades) in such a way that the fluid closer to the inner core will travel around the circuit in a certain relationship to the fluid closer to the other periphery.

Further, the situation is not improved if the pump part of the new system is changed so as to correct the stream for a blade system for any one particular Ms range. Any correction of the stream must be applicable for each combination of pump and turbine blade rings. This problem is solved according to the invention with a blade component which is relatively simple to manufacture in many different shapes and which is inserted in the circuit as a second part or outlet portion of the second ring of turbine blades. By modifying the shape of the blades of this part, it is possible to improve the fluid flow in the working chamber in general and the fluid approaching the inlets of the pump blades in particular. However, the shape of the part ought to be modified each time any other part of the blade system is modified so as to give the best performance for the torque converter. The same effect could be attained by having a single row of second turbine blades of threedimensional form but, in such instances, the manufacturing techniques employed would be more expensive. Our experience has shown, however, that it is exceedingly difficult, with such a three-dimensional second turbine, to obtain a sufficiently accurate shape. This is due to the fact that whereas it is easy to manufacture such three-dimensional blades per se by, for instance, the lost-wax method, integral casting of the I whole of the second turbine by the lose-wax method costs. At the same time, the invention offers the possibility of varying the blade shape so as to correct the stream. In addition, it is possible to extend the pump blades into the outer transition region, thereby obtaining high Ms values for the same basic blade system.

A comparison of FIGS. 1 and 2 shows that the part of the inner core defining the inner periphery of the outer transition region is extended into the inflow part of the working chamber. An extension of the pump on the core and into the outer transition region, that is, extending around the largest dimension of the working chamber and into the inflow or turbine region is now feasible, which also contributes to an improvement of the flow due to the shape of the outlet of the second turbine and inlet portion of the pump.

In comparison with known blade systems, the blade system of the present invention has the advantages of manufacturing exactness coupled with low manufacturing costs, and these factors are contributory in satisfying the demand of a greater potential market. In addition, the present blade system establishes, inter alia, a more uniform flow pattern which in its turn reduces the number of variances of two-dimensional blade ring elements necessary to obtain a wide Ms range. Alternatively, and if preferred, the invention may be used simply to increase the performance for any selected Ms range.

As an example of the benefits of the present invention it is noteworthy that a variation of the outlet angle over substantially the whole of the length of the blades of the second part of the second turbine blade ring minimizes losses of fluid flow. At the same time such a variation influences the spread of the inlet direction to different blade rows within the toroidal working chamber, and this in itself directly widens the utility range.

Another benefit of the present invention is that the modified turbine blades may be used with the same ring of pump blades having their outlet portions extending somewhat more than is conventionally the case onto 7 the outer transition region.

Generally speaking therefore, most of the features of a three-dimensional blade system are incorporated in the present invention in a blade system including principally two-dimensional rings of The the position within the blade system of the three-dimensional part, that is, the second part of the second turbine, is an important factor and permits the same to be readily removed from the blade system to effect a change in the characteristics of the torque converter by replacing the same with an alternative three-dimensional part.

The distribution of outlet angle of the blades in the second part of the second turbine ring not only affect the flow pattern of fluid within the toroidal chamber but create a better balance of forces at different speed ratios obtainable using the blade system. This can be achieved by die-casting the second part of the second turbine to the particular shape required.

An arrangement showing a means for angularly displacing the blades of the second part of the second turbine ring about their axes of symmetry, as described above, is shown in FIGS. 8-10 wherein the blade 50 is engaged at its lower end by a rod 51 which would be servo-operated to turn the blade about its axis of symmetry between closed and open positions as shown in FIGS. 10A and 108, respectively.

To assist in an understanding of the invention it is necessary to understand that, in a torque converter blade system, a modification in one blade ring influences practicallyall conditions in the system. Thus, if a loss is increased or incurred in one place (especially if this loss isin the low or high N /N range) it will also increase the losses at all other blade entrances due to the reduction in the quantity of fluid circulated. The 7 losses resulting from the first mentioned loss normally increases other losses in the system until an inferior balance is reached. On the other hand, and in contrast to the foregoing, an improvement in one region will result in an overall improvement of the system. Consequently, a modification of the second turbine outlet 'will suddenly allow an extension of the pump and render possible a reduction of entry losses into the first turbine and guide ring.

What we claim is:

. l. A hydrodynamic torque converter comprising:

means defining a toroidal working chamber comprising, a fluid outflow region in which the fluid flows radially outwardly, a fluid inflow region in which the fluid flows radially inwardly, an inner transition region in which the fluid flows from the inflow region to the outflow region and an outer transition region in which the fluid flows from said outflow region to said inflow region,

a ring of pump blades, a ring of guide blades and a ring of turbine blades, all of said rings located in the said working chamber, the blades of all rings forming channels having lengths extending generally across the fluid flow path in the toroidal working chamber,

at least a portion of one of said blade rings positioned in one of said transition regions, each of said blades in the transition region being three-dimensional such that the said channels formedby this ring present to the working fluid outlet angles which vary along their lengths; and

the blades of the remaining rings being principally two-dimensional such that the channels of said remaining rings present to the working fluid outlet angles which are the samealong their lengths.

2. A torque converter according to claim- 1, said turbine blade rings mounted on a hub, and wherein the blade ring in the transition region is positioned in the ,said inner transition region, preceding the. pump ring, considered "in thedirection of i'lu'id flow" in the working chamber,.and is connecteduothe'saidhubEof the tu'rlbine blade ring. g I 3 3. A torque converter according to claim l, in which the said blade ring in the transition region is a part of the saidpum pring' and is placed in .the said outer transition region, thereby serving toadjust theflow of fluid in the working chamber and the torque absorption of the ring of pump blades.

4. A torque converter according to claim 3, said turbine blade rings mounted on a hub, and wherein the radially outwardly, a fluid inflow region in which the fluid flows radially inwardly, an inner transition region in which the fluid flows from the inflow region to the outflow region and an outer transition region in which the fluid flows fromsaid outflow region to said inflow region,

a ring of pump blades located primarily in the outflow region, a ring of guide blades located in the inflow region, and at least first and second rings of turbine blades located at least in part in the inflow region,

the blades of said second ring of the turbine blade rings comprising a firs portion and a second portion, the first portion positioned principally in the inflow region, and the second portion positioned principally in the inner transition region,

the said second portion including means for controlling the flow conditions of fluid at the inlet of at least the blades of the pump ring.

6. A torque converter according to claim 5, the blades of all said rings forming channels having lengths extending generally across the toroidal fluid flow path within the toroidal chamber, the blades of the said first portion of the said second ring of the turbine blades being principally two-dimensional such that the channels formed thereby present to the working fluid outlet angles which are the same along their lengths, and wherein the said controlling means of the second portion comprises the construction wherein the blades of that portion are three-dimensional blades, the channels of which present to the working fluid outlet angles which vary along their lengths, the said first and second portions being fixed for rotation with each other.

7. A torque converter according to claim 6, wherein the first and second portions of the second turbine ring are separate parts, both of which are carried on a turbine ring holding member which is adapted to be mounted on aturbine shaft.

8. A torque converter according to claim 7, wherein the angle of the trailing ends of the three dimensional blades are varied along their lengths to adjust the direction of fluid flow along substantially the total length of the inlet portions of the pump ring blades.

9. A torque converter according to claim 6, wherein the said three-dimensional blades do not overlap their adjacent blades.

10. A torque converter according to claim 7, wherein the outlet angles of the said three-dimensional blades are varied along their lengths to balance the flow of fluid within the toroidal chamber so as to obtain minimum losses at high and low speed ratios.

11. A torque converter according to claim 6, wherein the first and second portions are separate first and second parts, respectively, connected together for rotation with each other, and wherein the blades of the first part of the second turbine ring are made an integral part of a turbine hub, whereby the turbine is suitable for casting and for transmitting high torque.

12. A torque converter according to claim 11 in which the blades of the first part of the second turbine have an axial draft relative to the turbine hub suitable for casting.

13. A torque converter according to claim 6, the said first and second portions being separate first and second tpjarts, respectively, connected together for rotation Wl each other, w erem the second part of the second turbine ring is die-cast or cast and shaped such that cores are not required during the casting.

14. A torque converter according to claim 13 in which the said second part of the second turbine ring is made of steel.

15. A torque convertor according to claim 6 in which the said second part of the second turbine ring is axially fixed between an inner core located in the center of the toroidal chamber and a turbine hub and maintained in such a position rotationally, in relation to the first part of the second turbine ring that the entrance of the said second part overlies the outlet of the said first part.

16. A torque converter according to claim 15 in which the second part of the second turbine ring is rotationally fixed both in relation to the said inner core and to the said turbine hub.

17. A torque converter according to claim 15 including an inner core, said inner core connected to the pump blades, and in which the said inner core of the pump blades extends into the outer transition region.

18. A torque converter according to claim 17 in which the pump blades extend into the outer transition region.

19. A torque converter according to claim 6, wherein the first and second portions are separate first and second parts, respectively, connected together for rotation with each other, and wherein the blades of the first part of the second turbine have their planes of symmetry disposed substantially radially with respect to the axis of rotation of the turbine.

20. A torque converter according to claim 6, the said first and second portions being separate first and second parts, respectively, connected together for rotation with each other, and wherein the second part of the second turbine ring is precision-cast.

21. A torque converter according to claim 6, the said first and second portions being separate first and second parts, respectively, connected together for rotation with each other, and including means for varying the outlet angles of the blades of said second part.

22. A torque converter according to claim 21, the last said means including means for turning the said blades of the second part about their axes of symmetry to vary the angular positions of said blades relative to the blades of the first part of the second ring of turbine blades.

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1. A hydrodynamic torque converter comprising: means defining a toroidal working chamber comprising, a fluid outflow region in which the fluid flows radially outwardly, a fluid inflow region in which the fluid flows radially inwardly, an inner transition region in which the fluid flows from the inflow region to the outflow region and an outer transition region in which the fluid flows from said outflow region to said inflow region, a ring of pump blades, a ring of guide blades and a ring of turbine blades, all of said rings located in the said working chamber, the blades of all rings forming channels having lengths extending generally across the fluid flow path in the toroidal working chamber, at least a portion of one of said blade rings positioned in one of said transition regions, each of said blades in the transition region being three-dimensional such that the said channels formed by this ring present to the working fluid outlet angles which vary along their lengths; and the blades of the remaining rings being principally twodimensional such that the channels of said remaining rings present to the working fluid outlet angles which are the same along their lengths.
 2. A torque converter according to claim 1, said turbine blade rings mounted on a hub, and wherein the blade ring in the transition region is positioned in the said inner transition region, preceding the pump ring, considered in the direction of fluid flow in the working chamber, and is connected to the said hub of the turbine blade ring.
 3. A torque converter according to claim 1, in which the said blade ring in the transition region is a part of the said pump ring and is placed in the said outer transition region, thereby serving to adjust the flow of fluid in the working chamber and the torque absorption of the ring of pump blades.
 4. A torque converter according to claim 3, said turbine blade rings mounted on a hub, and wherein the blade ring in the transition region further includes a blade ring positioned in the inner transition region, preceding the pump ring, considered in the direction of fluid flow in the working chamber, and being connected to the said hub of the turbine blade ring.
 5. A hydrodynamic torque converter comprising: means defining a toroidal working chamber comprising, a fluid outflow region in which the fluid flows radially outwardly, a fluid inflow region in which the fluid flows radially inwardly, an inner transition region in which the fluid flows from the inflow region to the outflow region and an outer transition region in which the fluid flows from said outflow region to said inflow region, a ring of pump blades located primarily in the outflow region, a ring of guide blades located in the inflow region, and at least first and second rings of turbine blAdes located at least in part in the inflow region, the blades of said second ring of the turbine blade rings comprising a firs portion and a second portion, the first portion positioned principally in the inflow region, and the second portion positioned principally in the inner transition region, the said second portion including means for controlling the flow conditions of fluid at the inlet of at least the blades of the pump ring.
 6. A torque converter according to claim 5, the blades of all said rings forming channels having lengths extending generally across the toroidal fluid flow path within the toroidal chamber, the blades of the said first portion of the said second ring of the turbine blades being principally two-dimensional such that the channels formed thereby present to the working fluid outlet angles which are the same along their lengths, and wherein the said controlling means of the second portion comprises the construction wherein the blades of that portion are three-dimensional blades, the channels of which present to the working fluid outlet angles which vary along their lengths, the said first and second portions being fixed for rotation with each other.
 7. A torque converter according to claim 6, wherein the first and second portions of the second turbine ring are separate parts, both of which are carried on a turbine ring holding member which is adapted to be mounted on a turbine shaft.
 8. A torque converter according to claim 7, wherein the angle of the trailing ends of the three dimensional blades are varied along their lengths to adjust the direction of fluid flow along substantially the total length of the inlet portions of the pump ring blades.
 9. A torque converter according to claim 6, wherein the said three-dimensional blades do not overlap their adjacent blades.
 10. A torque converter according to claim 7, wherein the outlet angles of the said three-dimensional blades are varied along their lengths to balance the flow of fluid within the toroidal chamber so as to obtain minimum losses at high and low speed ratios.
 11. A torque converter according to claim 6, wherein the first and second portions are separate first and second parts, respectively, connected together for rotation with each other, and wherein the blades of the first part of the second turbine ring are made an integral part of a turbine hub, whereby the turbine is suitable for casting and for transmitting high torque.
 12. A torque converter according to claim 11 in which the blades of the first part of the second turbine have an axial draft relative to the turbine hub suitable for casting.
 13. A torque converter according to claim 6, the said first and second portions being separate first and second parts, respectively, connected together for rotation with each other, wherein the second part of the second turbine ring is die-cast or cast and shaped such that cores are not required during the casting.
 14. A torque converter according to claim 13 in which the said second part of the second turbine ring is made of steel.
 15. A torque convertor according to claim 6 in which the said second part of the second turbine ring is axially fixed between an inner core located in the center of the toroidal chamber and a turbine hub and maintained in such a position rotationally, in relation to the first part of the second turbine ring that the entrance of the said second part overlies the outlet of the said first part.
 16. A torque converter according to claim 15 in which the second part of the second turbine ring is rotationally fixed both in relation to the said inner core and to the said turbine hub.
 17. A torque converter according to claim 15 including an inner core, said inner core connected to the pump blades, and in which the said inner core of the pump blades extends into the outer transition region.
 18. A torque converter according to claim 17 in which the pump blades extend into the outer transition region.
 19. A torque converter accoRding to claim 6, wherein the first and second portions are separate first and second parts, respectively, connected together for rotation with each other, and wherein the blades of the first part of the second turbine have their planes of symmetry disposed substantially radially with respect to the axis of rotation of the turbine.
 20. A torque converter according to claim 6, the said first and second portions being separate first and second parts, respectively, connected together for rotation with each other, and wherein the second part of the second turbine ring is precision-cast.
 21. A torque converter according to claim 6, the said first and second portions being separate first and second parts, respectively, connected together for rotation with each other, and including means for varying the outlet angles of the blades of said second part.
 22. A torque converter according to claim 21, the last said means including means for turning the said blades of the second part about their axes of symmetry to vary the angular positions of said blades relative to the blades of the first part of the second ring of turbine blades. 